ClickHouse/dbms/include/DB/Dictionaries/ClickHouseDictionarySource.h
2016-04-10 07:00:00 +03:00

131 lines
4.1 KiB
C++

#pragma once
#include <DB/Dictionaries/IDictionarySource.h>
#include <DB/Dictionaries/DictionaryStructure.h>
#include <DB/Dictionaries/ExternalQueryBuilder.h>
#include <DB/Client/ConnectionPool.h>
#include <DB/DataStreams/RemoteBlockInputStream.h>
#include <DB/Interpreters/executeQuery.h>
#include <DB/Common/isLocalAddress.h>
#include <ext/range.hpp>
#include <Poco/Util/AbstractConfiguration.h>
#include "writeParenthesisedString.h"
namespace DB
{
namespace ErrorCodes
{
extern const int UNSUPPORTED_METHOD;
}
const auto max_connections = 16;
/** Allows loading dictionaries from local or remote ClickHouse instance
* @todo use ConnectionPoolWithFailover
* @todo invent a way to keep track of source modifications
*/
class ClickHouseDictionarySource final : public IDictionarySource
{
public:
ClickHouseDictionarySource(const DictionaryStructure & dict_struct_,
const Poco::Util::AbstractConfiguration & config,
const std::string & config_prefix,
const Block & sample_block, Context & context)
: dict_struct{dict_struct_},
host{config.getString(config_prefix + ".host")},
port(config.getInt(config_prefix + ".port")),
user{config.getString(config_prefix + ".user", "")},
password{config.getString(config_prefix + ".password", "")},
db{config.getString(config_prefix + ".db", "")},
table{config.getString(config_prefix + ".table")},
where{config.getString(config_prefix + ".where", "")},
query_builder{dict_struct, db, table, where},
sample_block{sample_block}, context(context),
is_local{isLocalAddress({ host, port })},
pool{is_local ? nullptr : std::make_unique<ConnectionPool>(
max_connections, host, port, db, user, password,
"ClickHouseDictionarySource")
},
load_all_query{query_builder.composeLoadAllQuery()}
{}
/// copy-constructor is provided in order to support cloneability
ClickHouseDictionarySource(const ClickHouseDictionarySource & other)
: dict_struct{other.dict_struct},
host{other.host}, port{other.port}, user{other.user}, password{other.password},
db{other.db}, table{other.table},
where{other.where},
query_builder{dict_struct, db, table, where},
sample_block{other.sample_block}, context(other.context),
is_local{other.is_local},
pool{is_local ? nullptr : std::make_unique<ConnectionPool>(
max_connections, host, port, db, user, password,
"ClickHouseDictionarySource")},
load_all_query{other.load_all_query}
{}
BlockInputStreamPtr loadAll() override
{
/** Query to local ClickHouse is marked internal in order to avoid
* the necessity of holding process_list_element shared pointer.
*/
if (is_local)
return executeQuery(load_all_query, context, true).in;
return new RemoteBlockInputStream{pool.get(), load_all_query, nullptr};
}
BlockInputStreamPtr loadIds(const std::vector<std::uint64_t> & ids) override
{
return createStreamForSelectiveLoad(
query_builder.composeLoadIdsQuery(ids));
}
BlockInputStreamPtr loadKeys(
const ConstColumnPlainPtrs & key_columns, const std::vector<std::size_t> & requested_rows) override
{
return createStreamForSelectiveLoad(
query_builder.composeLoadKeysQuery(
key_columns, requested_rows, ExternalQueryBuilder::IN_WITH_TUPLES));
}
bool isModified() const override { return true; }
bool supportsSelectiveLoad() const override { return true; }
DictionarySourcePtr clone() const override { return std::make_unique<ClickHouseDictionarySource>(*this); }
std::string toString() const override
{
return "ClickHouse: " + db + '.' + table + (where.empty() ? "" : ", where: " + where);
}
private:
BlockInputStreamPtr createStreamForSelectiveLoad(const std::string query)
{
if (is_local)
return executeQuery(query, context, true).in;
return new RemoteBlockInputStream{pool.get(), query, nullptr};
}
const DictionaryStructure dict_struct;
const std::string host;
const UInt16 port;
const std::string user;
const std::string password;
const std::string db;
const std::string table;
const std::string where;
ExternalQueryBuilder query_builder;
Block sample_block;
Context & context;
const bool is_local;
std::unique_ptr<ConnectionPool> pool;
const std::string load_all_query;
};
}